1. Field
The exemplary embodiments of the invention herein relate to a display device, and particularly to, a substrate polishing apparatus capable of easily polishing substrates with various sizes.
2. Description of the Related Art
In general, display devices include a plurality of electronic elements driving pixels. When a display device is manufactured, electronic elements are provided on a substrate. A low temperature polysilicon (“LTPS”) process may be used to form a semiconductor layer of electronic elements.
The low temperature polysilicon process is a process in which amorphous silicon disposed on the substrate is crystallized to polysilicon having high electron mobility at a low temperature. During the low polysilicon process, an Eximer laser annealing process in which amorphous silicon is irradiated with an Eximer laser is performed.
When the low polysilicon process is performed, amorphous silicon is melt and is then changed into polysilicon while being cooled into a solid state. Here, protrusions are disposed on a surface of the polysilicon. To remove these protrusions, a substrate polishing apparatus is used. Methods for polishing substrates are subdivided into chemical polishing methods and mechanical polishing methods.
A substrate polishing apparatus used in chemical polishing methods includes an upper plate adsorbing a substrate, a pad polishing the substrate, a lower plate disposed under the upper plate, and a slurry supply part supplying the lower plate with slurry which is a chemical polishing agent.
The lower plate rotates in a predetermined direction, and the upper plate moves on the lower plate while rotating in a predetermined direction. A surface of the substrate is polished by the slurry supplied between the polishing pad and the substrate.